Reflective polarizer with integrated anti-reflective coating

Abstract

A multilayer polymer thin film includes an anti-reflective coating directly overlying a reflective polarizer stack. The reflective polarizer stack includes alternating first and second polymer layers, where the first layers include an isotropic polymer thin film and the second layers include an anisotropic polymer thin film. The anti-reflective coating (ARC) includes alternating third and fourth layers, where the third layers include an isotropic polymer thin film or an anisotropic polymer thin film and the fourth layers include an isotropic polymer thin film. The multilayer polymer thin film may be formed by co-extrusion where the reflective polarizer stack and the anti-reflective coating are formed simultaneously.

What is claimed is: 
     
         1 . A multilayer polymer thin film comprising:
 a reflective polarizer (RP) comprising alternating first and second layers, wherein the first layers each comprise an isotropic polymer thin film having in-plane refractive indices n x (1) and n y (1) and the second layers each comprise an anisotropic polymer thin film having in-plane refractive indices n x (2) and n y (2); and   an anti-reflective coating (ARC) located directly over the reflective polarizer, the anti-reflective coating comprising alternating third and fourth layers, wherein the third layers each comprise an isotropic polymer thin film or an anisotropic polymer thin film having in-plane refractive indices n x (3) and n y (3) and the fourth layers each comprise an isotropic polymer thin film having in-plane refractive indices n x (4) and n y (4).   
     
     
         2 . The multilayer polymer thin film of  claim 1 , having an average reflection of less than approximately 1% over a range of 400 nm to 700 nm along a pass direction, and an average reflection of at least approximately 90% over a range of 400 nm to 700 nm along a block direction. 
     
     
         3 . The multilayer polymer thin film of  claim 1 , wherein n x (1)<1.8, n y (1)<1.8, n x (1)−n y (1)<0.1, n x (2)>1.8, and n x (2)−n y (2)>0.1. 
     
     
         4 . The multilayer polymer thin film of  claim 1 , wherein n x (2)>1.85 and n x (2)−n y (2)>0.2. 
     
     
         5 . The multilayer polymer thin film of  claim 1 , wherein the second layers comprise a moiety selected from the group consisting of polyethylene naphthalate, polyethylene terephthalate, polybutylene naphthalate, polybutylene terephthalate, polyoxymethylene, and derivatives thereof. 
     
     
         6 . The multilayer polymer thin film of  claim 1 , wherein n x (3)>1.6, n y (3)>1.6, n x (3)−n y (3)<0.1, n x (4)<1.6, n y (4)<1.6, and n x (4)−n y (4)<0.1. 
     
     
         7 . The multilayer polymer thin film of  claim 1 , wherein n y (3)>1.6, n y (3)>n y (1), n x (4)<1.6, n y (4)<1.6, and n x (4)−n y (4)<0.1. 
     
     
         8 . The multilayer polymer thin film of  claim 1 , comprising a sacrificial layer disposed directly over at least one of the reflective polarizer and the anti-reflective coating. 
     
     
         9 . The multilayer polymer thin film of  claim 8 , wherein the sacrificial layer comprises a moiety having a surface energy of less than approximately 38 dyne/cm. 
     
     
         10 . The multilayer polymer thin film of  claim 8 , wherein the sacrificial layer comprises a moiety selected from the group consisting of polyethylene, polypropylene, and a fluorinated polymer. 
     
     
         11 . A method comprising:
 extruding alternating first and second polymer layers to form a reflective polarizer (RP) stack;   extruding alternating third and fourth polymer layers to form an anti-reflective coating directly overlying the reflective polarizer (RP) stack to form a multilayer polymer thin film comprising the reflective polarizer stack and the anti-reflective coating, wherein the reflective polarizer (RP) stack and the anti-reflective coating are extruded simultaneously; and   applying an in-plane stress to the multilayer polymer thin film.   
     
     
         12 . The method of  claim 11 , comprising forming a sacrificial layer directly over at least one of the reflective polarizer stack and the anti-reflective coating. 
     
     
         13 . The method of  claim 11 , further comprising co-extruding a sacrificial polymer layer directly over at least one of the reflective polarizer stack and the anti-reflective coating. 
     
     
         14 . The method of  claim 11 , further comprising co-extruding a sacrificial polymer layer directly over the anti-reflective coating and applying the in-plane stress to the multilayer polymer thin film prior to removing the sacrificial layer. 
     
     
         15 . The method of  claim 11 , wherein applying the in-plane stress comprises:
 attaching a clip array to opposing edges of the multilayer polymer thin film, the clip array comprising a plurality of first clips slidably disposed on a first track located proximate to a first edge of the multilayer polymer thin film and a plurality of second clips slidably disposed on a second track located proximate to a second edge of the multilayer polymer thin film;   applying a positive in-plane strain to the multilayer polymer thin film along a transverse direction by increasing a distance between the first clips and the second clips; and   decreasing an inter-clip spacing amongst the first clips and amongst the second clips along a machine direction while applying the in-plane strain.   
     
     
         16 . The method of  claim 11 , comprising heating the multilayer polymer thin film to a temperature greater than a glass transition temperature of at least one component of the multilayer polymer thin film while applying the in-plane stress. 
     
     
         17 . The method of  claim 11 , comprising laminating the multilayer polymer thin film to a transparent substrate. 
     
     
         18 . A multilayer polymer thin film comprising:
 a reflective polarizer (RP) comprising alternating first and second layers, wherein the first layers each comprise an isotropic polymer thin film and the second layers each comprise an anisotropic polymer thin film; and   an anti-reflective coating (ARC) located directly over the reflective polarizer, the anti-reflective coating comprising alternating third and fourth layers, wherein the third layers each comprise an isotropic polymer thin film or an anisotropic polymer thin film and the fourth layers each comprise an isotropic polymer thin film, wherein an in-plane refractive index n x (1) of the first layers is less than an in-plane refractive index n x (2) of the second layers, and an in-plane refractive index n x (3) of the third layers is greater than an in-plane refractive index n x (4) of the fourth layers.   
     
     
         19 . The multilayer polymer thin film of  claim 18 , comprising a sacrificial layer disposed directly over at least one of the reflective polarizer and the anti-reflective coating. 
     
     
         20 . The multilayer polymer thin film of  claim 19 , wherein the sacrificial layer comprises a moiety selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, polydimethylsiloxane, polypropylene, polyethylene, ethylene-vinyl acetate, polyoxymethylene, polystyrene, polyvinyl alcohol, and derivatives thereof.